The present invention relates to a silicone rubber microsuspension and to a method for the preparation thereof. More particularly, the present invention relates to a silicone rubber microsuspension which has an excellent high-concentration storage stability and to a method for the preparation thereof.
Removal of water from a silicone rubber microsuspension yields a microparticulate silicone rubber, which itself can be employed as an internal stress-relaxing material, lubricant, or filler for organic resin. This application requires that the silicone rubber microsuspension have an excellent storage stability at high concentrations and that its silicone rubber have a small average particle diameter.
Silicone rubber microsuspensions prepared by mixing a liquid silicone rubber composition with a surfactant and water in order to prepare an emulsion of said liquid silicone rubber composition and by subsequently curing said liquid silicone rubber composition have been described in Japanese Patent Publication Number 58-17226 [17,226/83], Japanese Patent Application Laid-Open [Kokai or Unexamined] Number 62-243621 [243,621/87], and Japanese Patent Application Laid-Open [Kokai or Unexamined] Number 01-306471 [306,471/89].
However, these prior methods are unable to produce a highly storage-stable, high-concentration silicone rubber microsuspension in which the silicone rubber has a small average particle diameter.
As a result of extensive efforts directed at solving the aforementioned problems, the present inventors have discovered a silicone rubber microsuspension which is free of these problems and a method for the preparation of same, based on the use of at least two types of nonionic surfactants with different HLB (hydrophilic-lipophilic balance) values. The present invention was achieved based on this finding.